1. Field of the Invention
The present invention relates to a process chamber and more specifically, a process chamber in which plasma enhanced chemical vapor deposition, sputtering, and other similar processes are performed on a substrate such as glass.
2. Discussion of Related Art
A multitude of general processes such as chemical vapor deposition, sputtering, etching and other similar processes can be carried out in a process chamber, for example, for forming layers of a thin film transistor on a substrate.
In the present description, a thermal process such as annealing is used as an example of a process performed in the process chamber. In a thermal process, a substrate that is disposed on a stage has heat transferred to the substrate via a heating coil that transforms electric energy into thermal energy. The heating coil heats the substrate so as to maintain a temperature that can accelerate the reaction between the substrate and process gases flowing in the process chamber.
FIG. 1 is a cross-sectional view of a stage according to the related art. FIG. 2 is a cross-sectional view of a process chamber including the stage shown in FIG. 1.
The stage shown in FIGS. 1 and 2 is a unitary, integral member including both a main base portion 100 and a substrate mounting portion 160.
Referring to FIG. 1 and FIG. 2, a stage is installed at the lower portion of the process chamber. The stage includes the main base portion 100, the substrate mounting portion 160, a heating coil 104, and a power supply 110.
The substrate mounting portion 160 protrudes upward and is located at the top part of the base portion 100. The base portion 100 also includes a built-in heating coil 104. The power supply 110 connects to the heating coil 104 so that by supplying the heating coil 104 with electric current, the heating coil 104 can transform electric energy to thermal energy.
Thus, the base portion 100 and the substrate mounting portion 160 define a unitary stage according to the related art.
Note that recesses on either side of the related art substrate mounting portion 160 are provided to accommodate fixing members (not shown) such as a fixing jig referred to as a xe2x80x9cshadow framexe2x80x9dto hold a substrate 140 on the substrate mounting portion 160.
When a substrate 140 is to be processed in the chamber, the substrate 140 is placed on the substrate mounting portion 160 and securing the shadow frames to the recesses at ends of the substrate mounting portion 160 to hold the substrate 140 in place on the substrate mounting portion 160 during the thermal processing in the chamber.
The substrate mounting portion 160 is usually made of aluminum, but can also be made of ceramic or quartz. The substrate mounting portion 160 is usually made of aluminum because quartz and ceramic are much more expensive materials and damaged easily because they react with F radical of process gas.
Also, because ceramic is lower heat conductivity than aluminum, it takes long time to heat ceramic.
So, they are The substrate mounting portion 160 made of aluminum requires an insulating layer disposed between the substrate mounting portion and the substrate in order to protect the substrate and to prevent the aluminum material from conducting current from the aluminum to the substrate thereby causing damage to TFT layers (not shown) later formed on the substrate during processing in the chamber.
A bellows 130 is placed at the exterior lower surface of the process chamber 150 so that the base portion 100 and the process chamber 150 is sealed. A support 106 includes a shaft 108 that rises or falls so as to maintain a proper distance between the substrate 140 and a gas emitting gas diffuser 154. Note that the gas diffuser 154 has a plurality of holes 156 so that gas from the gas supply 152 can be injected into the process chamber 150. Further, an outlet 158 exists at the bottom of the process chamber 150.
Process gas from the gas supply 152 is injected into the inner cavity of the process chamber 150 through the plurality of holes 156 defined in the gas diffuser 154. Note that the process gas turns into a plasma due to the RF power. A semiconductor layer (not shown) is formed on the substrate 140 as a result of the reaction of the process gas, in the plasma state, with the substrate 140. Note that to form the semiconductor layer, the substrate 140 has been mounted on the substrate mounting portion 160 and has been heated by the heating coil 104 to a temperature that is suitable for deposition of a film. Thereafter, the by-products from the thermal process are exhausted through the outlet 158.
Next, a related art process for maintaining a desired substrate temperature that is required for the above-described thermal process will be explained below.
The substrate 140 is placed on the substrate mounting portion 160 by a transporting unit(not shown in the drawing) such as a robot arm or other similar devices. Also, the proper distance between the gas diffuser 154 and the substrate 140 in the process chamber 150 is accomplished by having the shaft 108 rise or fall as needed for accurate positioning. Next, when the power supply 110 is turned on, the heat generated from the heating coil 104 conducts to the substrate mounting portion 160 and the substrate 140 disposed thereon, thus setting the proper temperature for the thermal process.
However, in the related art, the thermal process exposes the substrate mounting portion 160 to heat and gases that damage and contaminate the substrate mounting portion 160, and especially the surface protecting layer that is between the substrate mounting portion 160 and the substrate 140, if the substrate mounting portion is made of aluminum. If the substrate mounting portion 160 is made of quartz or ceramic, the substrate mounting portion 160 is also damaged by the heat and gases because quartz and ceramic materials react with F radical of process gas and ceramic is low heat conductivity.
Because the base portion 100 and the substrate mounting portion 160 define a major portion of a unitary stage, the whole stage must be replaced even though only the surface protecting layer or the substrate mounting portion 160 is damaged. The stage must also be replaced periodically with a new stage by opening the process chamber and then removing the stage from the chamber.
Further, the new stage needs to be set up again, thus consuming a large amount of process time and incurring additional costs.
To solve the problems described above, preferred embodiments of the present invention provide a process chamber that allows easy replacement of the substrate mounting member without having to replace the entire stage. Also, the present invention eliminates waste of process time and is constructed to allow very easy and quick replacement of a substrate mounting member.
One preferred embodiment of the present invention provides a process chamber including a main base, a substrate mounting member mounted on the main base and having a substrate mounted thereon, wherein the substrate mounting member is arranged to allow removal of the substrate mounting member.
Another preferred embodiment of the present invention provides a process chamber including a main base including a recessed portion and a protrusion at each of opposite ends thereof, a substrate mounting member mounted on the main base and arranged such that a portion of the substrate mounting member is disposed within the recessed portion of the main base and between the protrusions at the opposite ends of the main base.
Another preferred embodiment of the present invention provides a process chamber which preferably includes a main base, and a substrate mounting member which is independent of the main base and removably mounted on the main base, and arranged to support a substrate during processing.
In preferred embodiments of the present invention, the substrate mounting member may have a plurality of different shapes and configurations. Regardless of such different shapes, the substrate mounting member and the main base are constructed such that the shape of a portion of the mounting member mates with and correspondes to a shape of a top surface of the main base. Other features, elements, characteristics and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the present invention with reference to the attached drawings.